Multistep intake unloader



Aug 22, 1939-l c. wAlNwRlGHT 2,170,358

MULTI STEP INTAKE UNLOADER INVETOR Aug. 22, 1939.

c. wAlNwRlGHT MULTISTEP INTAKE UNLOADER Filed March 25, 1936 2 Sheets-Sheet 2 INVENTOR Patented Aug. 22, 1939 UNITED STATES PATENT OFFICE 9 Claims.

The invention relates to anintake unloader for compressors and more especially to a multi-step intake unloader.

The primary object of the invention isto provide an appliance of the kind indicated which is effective for unloading purposes when used in combination with the intake of a compressor and a multi-step governor of the general character of that disclosed in application No. 70,902, filed 10 March 25, 1936, and is automatic in operation to make possible the complete unloading of a high pressure cylinder of the compressor when the multi-step governor is working at no load.

Another object of the inventio-n is the provi- -sion of a device of this character, wherein the construction thereof is novel in form` and assures a step by step unloading of a compressor so as to relieve the same from a. compression load .and particularly when starting or stopping such compressor.

A further object of the invention is the provision-of a device of this character, which is comparatively simple in its construction, thoroughly reliable and eiiicacious in its operation, durable, automatic in the working thereof and inexpensive to manufacture and install.

With these and other objects in View, the invention consists in the features of construction; combination and arrangement of parts as will be hereinafter more fully described, illustrated in the accompanying drawings, which disclose the preferredy embodimentI of the invention and pointed out in the claims hereunto appended.

In the accompanying drawings:

Figure l is a sectional view through an un,- loader constructed in accordance with the invention for service in a four-step unloading operation i'or a compressor.

Figure 2 is a fragmentary plan viewfof the unloader associated with a two-cylinder two-stage compressor and a governor, respectively.

Figure 3 is a fragmentary sectional viewof an unloading valve, sometimes termedl a bly-pass'r 553ing piece I8 fitted Within the body I0 at thel (Cl. 23o-25) inner end of a cylinder extension I9 on said body I0. Fitting this extension I9 is a closure cap 20 having a guide cylinder 2| projected into said extension I9 and accommodating a slidable guide piston 22 tting said stem I'I. Surrounding the stem I? is a coiled unseating valve spring 23, which is supported by the centering piece I8 and contacts with a shoulder 24- formed on the stern II next to the piston 22 so that the valve I6 will be normally raised from its seat I5 thus allowing flow through the body I0 from one opening H to the other opening I2 therein.

The open end II has communication with` the intake 25 of the low pressure cylinder 26 of a two-cylinder two-step compressor while the open end t. affords an air inlet to said body I8.

Fitted centrally in the cap 2t of the extension I9 is a nipple 2l for the joining therewith of an unloader shell 28 having interiorly thereof stepped annular seats 29, 30 and 3I, respectively, while coacting with these seats are the pistons 32, 33Vand 34, respectively, these dividing the said shell 28 into separated unloading chambers. d, b, c and d, respectively. Fitting the pistons 32, 33 and 34 are the adjustable reach bolts v35, 36 and-3l, the latter bolt Working through the nipple 2l for contact with the piston A22 tting the guide cylinder 2i while the bolts 35 and 36 have contact with the pistons 33 and 3,4, respectively, maintaining the division of the chambers lc, bl, c andV d as constituted within the shell 28. The shell 28v is ttedwith an end head 38 having a depression 39 affording a clearance for the reach bolt 35V carried by the piston 32. These bolts 35, 36 .and 3l are centrally located in the said pistons.

Communicating with each of the chambers a, o, c` and dis a duct 48 and extending from these are pipes 4I, 42, 43 and 44, the pipe 4I being in communication with the chamberra', the pipe l42 in communication withthe chamber b, the pipe 43 in communication with the chamber c and the pipe 44 in communication with thel chamber d'. lThe pipe 44 throughH a standard electric: solencid operated valvel 45 alternately communicates With branch leads 46 and 41, the lead 46 being connected with an air receiver 48 by a line 49y extending to a governor 58 which is structurally like that shown in the application hereinbefore referred to. The air receiver 48 is that for the compressor and the line 49 communicates with the air cylinder of said governor 50. The lead 4l extendsto anunloadingor bypass Valve 5I of the high pressure cylinder 52 of the coni` pressor' andv alsoby line 53` with the cylinder oi" thevr governorll. The other unloading or bypass valve 54 of said cylinder 52 has the pipe 4I leading thereto and this pipe by line 55 has communication with the cylinder of the governor 50, The pipes 42 and 43 extend to the cylinder of the governor 5I).

Leading from the discharge side 56 of the high pressure cylinder 52 tothe distributor chamber of the governor 50 is a pipe 57 and tted with this pipe is a manually or automatically operated three-way valve 58, the purpose of the latter being that when in one position compressor air to the governor 53 and its connections is exhausted to the atmosphere and when in another position it furnishes compressor air to the said governor 513, the valve 58 being shown as oi the electric solenoid type similar to the valve 45 hereinbefore referred to. The valves 5I and 54 form communication between the ends of the cylinder,

52 and the intake chamber of such cylinder so that when these valves are open each at the particular end of the cylinder renders such end inoperative and when closed operative.

The stem Il of the valve I6 is limited in an upward travel so that the valve I6 has a definite upper limit of movement. The governor 50 in its type is of a ve-step control and the exhaust of this governor is indicated at 59.

lIn the operation of the unloader a predetermined terminal pressure is chosen for the compressor and the governor 50 is set to operate at this pressure. When this pressure is reached by the compressor the governor 50 goes into action and for the rst step compressed air is admitted through the pipe 4I into the chamber a forcing the piston 32 to its seat 29 and concurrently therewith moving the piston 22 downwardly in the cylinder 2| a distance equal thereto, that is, one-fourth of the distance to be traveled toward the seat I5 of the valve I6. If terminal air pressureV still goes higher compressed air ad- `mitted through line 55 to unloading valve 54 making that end of the cylinder 52 inoperative and at the same time furnishing compressed air to pipe 42 driving the piston 33 downward to its seat 'will cause the piston 22 and the valve I6 `to move another one-fourth of its total downward travel and thus such valve I6 will then be half closed. If the terminal air pressure still goes higher compressed air is admitted through pipe 43 into chamber c forcing the piston 34 to its seat su with the result that the piston 22 and the vaive I6 will have moved another definite distance so that the valve I6 will have approached its seat I5 another one-fourth travel of total downward movement and further increase in terminal air pressure compressed air is admitted through the pipes 44 and 41 into chamber d causing the piston 22 to be moved downwardly in the cylinder 2| to have the valve I6 come in contact with the seat I5 thus completely closing communication between the open ends I I and I2 in the body I0 and at the same time compressed air through the connection 41 with the unloading valve 5I is carried to said valve and thereby eiecting the high pressure cylinder or compressor to be completely unloaded.

By means of the solenoid valve 45, uid pressure from the receiver 48 can be introduced directly into the chamber d, since the operation vof closing the circuit on the solenoid will shift the starting and stopping of the compressor the compression load may be taken off or put on as may be deemed necessary.

From the foregoing it will be apparent that the unloading device is of a multi-step intake unloader for compressors and such unloading through these steps may be had of any fractional part of the maximum capacity of such compressor, in this instance the unloader being in quarter steps of maximum load capacity.

What is claimed is:

1. In combination with a compressor, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor to unload the latter, the improvement which comprises a valve disposed at the intake of the compressor and interposed in the connections between that and the governor to automatically vary the uid volume admitted and yieldingly impelled to open position, said valve being interposed in the connections between the governor and the compressor and provided with means coordinated with the governor to be moved toward closed vposition a distance in accordance with any step assumed by the governor in its unloading functions.

2. In combination with a compressor having high pressure and low pressure cylinders, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor cylinders to unload the latter, the improvement which comprises a valve disposed at the intake of the low pressure cylinder and interposed in the connections with the governor, the valve being normally impelled to open position and governor controlled for movement toward closed position to varying extents dependent on the position assumed by the governor in its unloading functions.

3. In combination with a compressor having high pressure and low pressure cylinders, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor cylinders to unload the latter, the improvement which comprises a valve positioned at the intake of the low pressure cylinder and yieldf ingly impelled to open position, said valve being interposed lin the connections between the governor and the cylinder and provided with means coordinated with the governor to be moved toward closed position a distance in accordance with any step assumed by the governor in its unloading functions.

4. In combination with a compressor having high pressure and low pressure cylinders, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor cylinders to unload the latter, the improvement which comprises a valve disposed at the intake of the low pressure cylinder and spring impelled to open position, the valve being interposed in the connections between the governor and the low pressure cylinder and provided with governor responsive means to move it to closing position and divide the closing movement into fractional parts of the full movement so that the iiuid volume admitted to the low pressure cylinder will be determined by the position of the governor in its unloading functions.

5. In combination with a compressor having high pressure and low pressure cylinders, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor cylinders to unload the latter, the improvement which comprises avalve disposed at 76 the intake of the low pressure cylinder and spring impelled to open position, the valve being interposed in the connections between the governor and the low pressure cylinder and provided with governor responsive means to move it to closing position and divide the closing movement into fractional parts of the full movement so that the fluid volume admitted to the low pressure cylinder will be determined by the position of the governor in its unloading functions, one of the connections between the governor and said valve being provided with means for selectively admitting receiver pressure direct to the valve to effect full closing movement of the latter.

6. In combination with a compressor having lhigh pressure and low pessure cylinders, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor cylinders to unload the latter, the improvement which comprises a valve disposed at the intake of the low pressure cylinder and spring impelled toward open position, a series of superposed operatively connected pistons, a shell surmounting the valve and enclosing the pistons and divided by the latter into chambers respectively in communication with the steps of the governor, the uppermost chamber being continuously in communication with its step of the governor and communication between the remaining chambers and the governor steps being controlled by the pistons, whereby movement of the valve toward closed position to control the uid volume admitted to the low pressure cylinder is varied in accordance with the particular step or steps of the governor that are functioning.

7. In combination with a compressor having high pressure and low pressure cylinders, an air receiver, and a multi-step governor operatively connected with the receiver and with the compressor cylinders to unload the latter, the improvement which comprises a valve disposed at the intake of the low pressure cylinder and spring impelled toward open position, a series of superposed operatively connected pistons, a shell surmcunting the valve and enclosing the pistons and divided by the latter into chambers respectively in communication with the steps of the governor, the uppermost chamber being continuously in communication with its step of the governor and communication between the remaining chambers and the governor steps being controlled by the pistons, whereby movement of the valve toward closed position to control the iluid volume admitted to the low pressure cylinder is varied in accordance with the particular step or steps of the governor that are functioning, the operative connections between the pistons being adjustable to vary the spacing between the same.

8. In a compressor system, compressor means having an air inlet, an intake unloader associated with the air inlet, the unloader comprising a valve, a housing provided with a plurality of axially aligned communicating bores of different diameters with each bore terminating in a ledge, a piston slidable in each bore, spacing means cooperable with said pistons for holding the latter in predetermined spaced relation, the spaces between the pistons constituting air inlet chambers and the piston of the largest diameter being spaced from an end wall of the housing to provide an air inlet chamber, said valve including a port and a valve element, a stem secured to said valve element guided i or movement longitudinally of the common axis of said bores, said valve element being movable toward and away from said port, a multi-step governor having connections with said housing for respective communication with said chambers, said multi-step governor responding to predetermined compressor discharge pressure for selectively admitting compressed air to said chambers, for successively moving said pistons to move said valve element corresponding distances toward a closed position with respect to said port, each piston being movable into seating relation upon the ledge associated with its respective bore, and resilient means for urging the valve element toward an open position.

9. In a compressor system, compressor means having an air inlet, an intake unloader associated with the air inlet, the unloader comprising a valve body having a port and a valve element for closing the port, a housing provided with a plurality of axially aligned communicating bores of different diameters with each bore terminating in a ledge, a piston slidable in each bore, spacing means cooperable with said pistons for holding the latter in predetermined spaced relation, the spaces between the pistons constituting air inlet chambers and the piston of the largest diameter being spaced from an end wall of the housing to provide an air inlet chamber, a stem secured t0 said valve element guided for movement longitudinally of the common axis of said bores, a cylinder having a closing piston abutting said stem and said closing piston being engaged by one of saicl spacing means, said valve element being movable toward and away from said port, a multi-step governor having connections with said housing for respective communication with said chambers and said cylinder, said multi-step governor responding to predetermined compressor discharge pressure for selectively admitting compressed air to said chambers and said cylinder, for successively moving said pistons to move said valve element corresponding distances toward a closed position with respect to said port, each piston being movable into seating reiation upon CHARLES WAINWRIGHT, 

